School science practical activities have been criticised for exposing learners to a series of phenomena disconnected from the conceptual frameworks needed to understand them. Such activities are successful in the "domain of observables" but not the "domain of ideas". Few resources exist for classroom teachers wishing to improve the effectiveness of practical activities in the domain of ideas. This report describes an action research project to develop a scaffold for biology practical lessons. This scaffold separates inquiry questions and the techniques needed to address them, and thus combines two approaches to scaffolding in a single tool ("problematising" and "reducing the degrees of freedom"). Analysis of the speech of 16-17 year olds in the study class (n = 23) was used to assess their engagement in the domain of ideas. Following the scaffold's introduction, the learners were found to speak more about relevant ideas and concepts during practical activities. When the scaffold was partially faded, the learners continued to demonstrate engagement with the domain of ideas. The approach reported here would seem to have much potential for supporting learning from "minds-on" biology practical work in a variety of contexts.